The Broad Perspective

Wetlands in San Francisco in 1850, sfbay.wr.usgs.govWetlands in San Francisco in 1990,

Images from the San Francisco bay region, California.

Green areas represent wetlands, red areas represent urban development. Yellow circles represent major earthquakes.

Since the settlement of Europeans into the New World, humans have being threatening the survival of wetlands. In fact, 54% of the wetlands that were present in the U.S. during settlement have been lost to anthropogenic causes (Kelly 2001, Semlitsch 1998). The loss is up to 90% of the original wetlands in some states, including Ohio (Weems and Canter 1995). In the post-settlement period, when agriculture was rapidly spreading throughout the U.S., wetlands were destroyed in order to create more agricultural land. In fact, the government advocated the destruction of "unproductive" wetlands to make room for agriculture. The government saw these wetlands as cesspools and breeding grounds for diseases (Mitsch and Gosselink 2000). Our concern has shifted from food production to human habitation, and now we are expanding cities and suburbs instead of agricultural land. Urban activities are expanding to previously rural areas in order to compensate for increasing human populations, resulting in the disturbance and loss of wetlands (Kelly 2001).

Today there is a greater understanding of wetland function and their importance to our environment. We know now that wetlands are a keystone ecosystem in our world; they have a disproportionate effect on the world from other ecosystems (Gopal 1999). One of the most important services wetlands provide us with is the stabilizing effect they have on our major water systems. Wetlands retain water in the event of a flood and provide water in the event of a drought (Mitsch and Gosselink 2000). They act as "kidneys" in our landscape by filtering sediments and pollution (especially nitrates) from inflows, thus acting as specialized riparian zones. Wetlands additionally serve as breeding and recruitment areas for many fauna and provide humans with food, such as cranberries, fish, shrimp, and oysters (Horne and Goldman 1994, Mitsch and Gosselink 2000).

The implications of wetland loss have been noted on both a local scale and a regional scale. On a local scale, species diversity is decreasing, oyster and shrimp industries are failing due to low recruitment, water foul are disappearing, flooding is increasing, and droughts are getting more severe. Regionally, water systems are becoming fouled with pollutants and sediment, affecting water quality from the source of the problem to the oceans hundreds of miles away (Rabalais et al. 1999). The draining of peatlands, a type of wetland, has been shown to increase rates of release of carbon dioxide and methane (Gorham 1991). The release of these greenhouse gases is a result of peat exposure and decay, during which these gases are emitted as a byproduct. These gases, however, are thought to largely contribute to global warming (Gorham 1991). In an experiment focusing on the effects of water levels and uptake of carbon dioxide by vegetation, it was found that lowering the water table of a peatland by only a few centimeters resulted in a strong decrease in carbon capture (Gorham 1991). This carbon release may contribute to increasing greenhouse effects, which will cause peatland evaporation, and the cycle will continue. We must begin to confront and rectify the problems we are creating for ourselves by protecting the wetlands that remain.

The government has implemented a wetland policy in the United States requiring that destroyed natural wetlands are replaced by created wetlands or restored wetlands through mitigation projects (Weems and Canter 1995). However, there are major problems with the policies, which assume parity of replacement and natural wetlands. In addition, the policy forcing creation of wetlands equally forces the destruction of a wetland ecosystem (in many cases prairie land) that is not biologically prepared to support a different ecosystem.